This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Hydrogels possess properties that make them extremely suitable for biomaterial applications. They are biocompatible, non-immunogenic, hydrophilic, porous, and can frequently be tuned for a desired function such as drug release. However, the mechanical weakness of the hydrogels often limits their application as replacement materials for natural tissues. To address issues of mechanical weakness, our research group has developed an interpenetrating polymer network (IPN) composed of tightly crosslinked, neutral poly(ethylene glycol) (PEG) as the first network and loosely crosslinked poly(acrylic acid) (PAA), an ionic polymer, as the second network. Our previous SAXS measurements have focused on the structure of individual PEG and PAA networks as well as the high strength IPNs. In the current proposal, we would like to explore the structural effects of incorporating hydrophobic biomolecules such as cholesterol as well as surfactant molecules into the network structure to enhance integration with biological systems. Additionally, we would like to further explore the effects of processing conditions on the hydrogel structure such as the solvent used for hydrogel preparation. The proposed SAXS measurements will aid in understanding how chemical and processing modifications to our hydrogel networks change the molecular level morphology of the materials. This work is necessary for in order to add tunability to our hydrogel system for enhanced design and capabilities.